2018 ASHS Annual Conference

Triplicate water samples were collected monthly from 9 waterways (8 recycling containment basins (RCBs) and 1 stream) on 4 commercial ornamental plant nurseries from February to July, and from 1 RCB and nursery from April to October. Four RCBs, one per nursery, were actively utilized as an irrigation water source. Analysis was done for 18 water quality variables including ammonium-nitrogen (NH₄⁺ -N), nitrate-nitrogen (NO₃^- -N), ortho phosphate-phosphorus (PO₄-P), Total-phosphorus (T-P), potassium, calcium, magnesium, sulfur, aluminum, boron, copper, iron, manganese, zinc, pH, total alkalinity (T-Alk), electrical conductivity and sodium. The degree and rate of monthly change varied considerably between RCBs. Macronutrients generally increased at most nurseries in one to two months after fertilizer application particularly in 3 RCBs (MD21, VA11 and VA12), with levels of N and P forms exceeding preferred criteria for irrigation water by June and July in VA11 and VA12. Micronutrients fluctuated less, but did vary per RCB with the most monthly change occurring in MD21. Even though pH fluctuated, pH tended to remain alkaline or neutral to acidic respective of the RCB during the entire sample period. T-Alk tended to increase over the summer. EC primarily fluctuated in RCBs with high macronutrient levels. Although levels of N- and P-forms were mostly suitable by irrigation water criteria, they were frequently above U.S. Environmental Protection Agency nutrient criteria for promoting healthy water environments of lakes and reservoirs, and are discussed.